The Three Pillars of Zen by Phillip Kapleau
https://terebess.hu/zen/mesterek/KapleauPillars.pdf

Zen Mind Beginner’s Mind by Shunryu Suzuki
https://holybooks.com/zen-mind-beginners-mind/

The Diamond Sutra is available in many English translations.  Links to several of them can be found here: https://terebess.hu/english/diamond.html.  Genpo Roshi references the translation which is included in The Diamond Sutra and the Sutra of Hui–Neng, translated by A. F. Price & Wong Mou-lam.  A PDF of this translation is available here: http://zen-ua.org/wp-content/uploads/the_diamond_sutra_english.pdf.

The Sixth Patriarch’s Sutra translated by the same translators, which Roshi recommends, is available online here: http://www.katinkahesselink.net/tibet/hui_neng1.html, and can be downloaded as a PDF here: https://terebess.hu/zen/PlatformPrice.pdf

Eight Beliefs in Buddhism by Hakuun Yasutani Roshi  https://bigmind.org/wp-content/uploads/2021/04/Yasutani-Eight-Beliefs-in-Buddhism.pdf

Modern Buddhist Masters by Jack Kornfield
https://archive.org/download/bub_gb_8InEkEp5FtEC/bub_gb_8InEkEp5FtEC.pdf

Embracing Our Selves by Hal and Sidra Stone

Embracing Each Other by Hal and Sidra Stone

Fascicles of Dogen Zenji’s Shobogenzo
Fukanzazengi (Recommendation for Zazen) , Uji (Being-Time), Genjokoan (Actualizing the Fundamental Point).  
Many translations can be found on the internet.  PDFs and notes about several can be found here: https://terebess.hu/zen/dogen/index.html.  To see how translations of Dogen Zenji can vary: 8 English Translations of Genjokoan

Record of Rinzai
PDFs and notes about several different translations can be found here: https://terebess.hu/zen/linji-eng.html
Genpo Roshi is most familiar with the translation edited by Ruth Fuller Sasaki

The Life and Teachings of Obaku (Huang-po)
PDFs and notes about several different translations can be found here: https://terebess.hu/zen/huangbo.html
Genpo Roshi is most familiar with the translation by John Blofeld